How to Measure RT60 Without Special Equipment

TL;DR

You do not need a dodecahedron speaker and a calibrated measurement microphone to get a useful RT60 measurement. A phone or laptop with SonaVyx can capture impulse responses using hand claps, balloon pops, or the built-in sweep generator played through any speaker. This guide shows how to get reliable RT60 data with consumer hardware.

Methods for Equipment-Free RT60

ISO 3382-1 specifies an omnidirectional source and measurement microphone, but for practical purposes (design verification, quick checks, trend monitoring), three simpler methods work:

Method 1: Hand Clap (Quickest)

Open SonaVyx IR tool at /tools/rt60 and select "Manual Impulse" mode.
Position your phone at the measurement position (1.2 m height, center of room or listening position).
Clap loudly once. A single sharp clap provides a broadband impulse. Stand at least 2 m from the phone to avoid near-field effects.
SonaVyx detects the impulse and computes the energy decay curve. The RT60 is extracted from the Schroeder backward integration. Repeat 3 times and average for better accuracy.

Method 2: Balloon Pop (Better SNR)

Inflate a balloon to near-maximum size (larger balloons produce more low-frequency energy).
Set SonaVyx to record mode. Position the phone at the receiver position.
Pop the balloon with a pin at the source position (where the speaker would be). The pop generates a short, loud impulse with better SNR than a hand clap, especially below 500 Hz.
Analyze the result. SonaVyx extracts T20, T30, and EDT from the energy decay curve. Check INR — balloon pops typically achieve 30-40 dB INR, sufficient for T20 but marginal for T30.

Method 3: Sine Sweep Through Any Speaker (Best Quality)

Connect a speaker — even a portable Bluetooth speaker works for mid-frequency RT60. Place it at the source position.
Open SonaVyx IR tool and select "Sine Sweep" mode. Set duration to 5-10 seconds.
Run the sweep. SonaVyx plays the logarithmic sweep through the speaker and captures it simultaneously. The deconvolution process extracts the impulse response with excellent SNR.
Review the results. Sweep method typically achieves 40-50 dB INR even with consumer speakers, making it reliable for T20 and T30 across 250 Hz to 4 kHz.

Accuracy Expectations

Method	Typical INR	Reliable Bands	Expected Accuracy
Hand clap	20-30 dB	500 Hz - 4 kHz	±0.3 s (T20 only)
Balloon pop	30-40 dB	250 Hz - 8 kHz	±0.2 s (T20, marginal T30)
Sweep + speaker	40-50 dB	125 Hz - 8 kHz	±0.1 s (T20 and T30)

Common Mistakes

Multiple claps. Double claps create overlapping impulse responses that confuse the analysis. One sharp clap only.
Standing too close to the phone. Your body blocks reflections and absorbs sound. Stand at least 2 m away, preferably move out of the measurement area entirely.
Measuring a very dry room with claps. If RT60 is below 0.5 s, the impulse decays too quickly for reliable extraction from a clap. Use the sweep method for treated rooms.
Reporting without caveats. Always note the method used: "RT60 measured via hand clap method — approximate, suitable for design verification, not ISO 3382-1 compliant."

Tool Bridge

Open the SonaVyx RT60 Tool to measure reverberation time with any of these methods. Results include T20, T30, EDT, and octave band breakdown.